KR100766894B1 - Method for fabricating field emission display device - Google Patents

Abstract

The present invention relates to a method for manufacturing a field emission display device capable of forming a negative hole having a fine hole width and improving uniformity between negative holes. The device manufacturing method of the present invention provides a photosensitive film on a lower substrate provided with a cathode electrode. Making a step; Exposing and developing the photosensitive film to form a photosensitive pillar at a position to form a negative hole; Forming an insulating film covering the photosensitive pillar; Firing the insulating film to vaporize the photosensitive pillar to dent a portion of the insulating film covering the pillar, or to form an empty space inside the insulating film; And etching the recessed portion or the portion having the empty space to form a negative hole.

FED, electric field, gate hole, pillar, photosensitive, etching, dent, pupil, firing, insulation, pillar

Description

Method for manufacturing field emission display device {METHOD FOR FABRICATING FIELD EMISSION DISPLAY DEVICE}

1 to 13 is a view showing the manufacturing process of the present invention,

1 shows a step of forming a cathode electrode;

2 shows a step of forming a photosensitive film.

3 shows a step of forming a photosensitive column.

4 is a view showing a state in which a photosensitive column is formed.

5 shows a step of forming an insulating film.

6 is a view showing a state in which the photosensitive pillar is removed.

7 is a view showing another embodiment in a state in which a photosensitive column is removed.

8 shows a step of forming a negative hole;

9 is a view showing a state in which a negative hole is formed.

10 is a view showing a state in which a gate electrode is formed.

11 is a view showing a state in which an electron emission layer is formed.

12 is a view showing another embodiment in a state in which an electron emission layer is formed.

13 illustrates a step of joining an upper substrate and a lower substrate.

The present invention relates to a method for manufacturing a tripolar field emission display device having an insulating layer provided with a negative hole, and more particularly, to form a negative hole having a fine hole width, and to improve uniformity between negative holes. A method for manufacturing a field emission display device.

As disclosed in US Pat. No. 3,665,241, early field emission indicators formed conical metal tips on cathode electrodes, formed gate electrodes around the metal tips, and voltages above the threshold voltage between both electrodes. A driving voltage is applied to generate a difference so that electrons are emitted from the metal tip, and the emitted electrons are accelerated by a fluorescent film attached to the anode electrode to implement a predetermined image.

However, since the field emission display device requires expensive semiconductor equipment to form the metal tip, the manufacturing cost increases, and it is difficult to implement a large area display due to a complicated manufacturing process.

In order to solve these problems, a field emission display device has been proposed which forms the electron emission layer into a plane.

The planar electron emission layer is typically a carbon-based material such as graphite, carbon fiber, diamond like carbon (DLC), or carbon nanotube (CNT). In recent years, carbon nanotubes (CNT) have been spotlighted as electron emission layers. This is because the end radius of curvature of the carbon nanotubes is about 100 μs, so that electron emission occurs smoothly even at an external voltage of about 10 to 50 V, so that low-voltage driving is easy and a large area can be obtained.

The field emission display device including the carbon-based material as an electron emission source is generally manufactured in a triode structure to easily control electron emission. The triode structure has a gate electrode interposed between an insulating layer and a cathode of the cathode electrode. The gate may be divided into an under gate structure disposed below and a normal gate structure positioned above the cathode with the gate electrode interposed therebetween.

In other words, the lower gate structure refers to a structure in which a cathode electrode is disposed between the gate electrode and the fluorescent film, and the general gate structure refers to a structure in which the gate electrode is disposed between the cathode electrode and the fluorescent film, and the present invention provides a general gate structure. Since the present invention relates to a field emission display device having a structure, only a general gate structure will be described below.

As described above, in the field emission display device having the general gate structure, since the gate electrode is disposed on the cathode electrode with the insulating film interposed therebetween, the electron emitted from the electron emission layer on the cathode electrode reaches the fluorescent film. A negative hole as a passage through which is passed should be provided in the insulating film.

Therefore, after the insulating film is formed to a certain height by a thin film process using vacuum deposition or a thick film process by printing a paste, a negative hole is formed using a known wet etching method, and undercutting is performed during the wet etching. Due to the cut phenomenon, it is not easy to form the negative hole finely and uniformly.

Here, the undercut phenomenon refers to the lower width of the negative hole is formed narrower than the upper width, this phenomenon is caused by the isotropic etching, that is, the etching progresses by the same distance in the circle at the beginning of the etching circle .

Therefore, the negative hole forming method using the wet etching has a limitation in manufacturing a high-resolution device.

SUMMARY OF THE INVENTION The present invention has been made to solve the above problems, and an object thereof is to provide a method of manufacturing a field emission display device capable of forming fine and uniformly negative holes through which electrons emitted from an electron emission layer pass.

The object of the present invention described above,

Forming a cathode on the lower substrate;

Forming a photoresist film on the lower substrate;

Exposing and developing the photosensitive film to form a photosensitive pillar at a position to form a negative hole;

Printing and drying an insulating paste on the lower substrate to form an insulating film covering the photosensitive pillar;

Firing the insulating film to vaporize the photosensitive pillar to dent a portion of the insulating film covering the pillar, or to form an empty space inside the insulating film;

Etching the recessed portion or the portion with empty space to form a negative hole;

Forming a gate electrode on the insulating layer, and etching the gate electrode to form a gate hole penetrating the negative hole;

Forming an electron emission layer on the cathode electrode inside the negative hole;

Arranging an upper substrate having an anode electrode and a fluorescent film substantially parallel to the lower substrate and combining the upper substrate to form a sealed container, and then evacuating the inside of the sealed container;

It is achieved by a method for manufacturing a field emission display device comprising a.

As described above, the present invention reduces the thickness of the insulating film in the portion requiring etching, and thus performs etching, thereby minimizing the occurrence of the undercut phenomenon due to the isotropic etching. Negative holes can be formed, and fine and uniform negative holes can be manufactured.

In carrying out the present invention, the insulating film can be formed on the lower substrate by printing, electrophoresis, doctor blade, or spray method.

In the firing operation of the insulating film, the solvent and the binder are removed by maintaining the temperature at 350 to 450 ° C. for 10 to 60 minutes, and then 5 to 60 at a temperature of 20 to 30 ° C. higher than the softening point (450 to 550 ° C.) of the insulator frit. The photoresist may be made of a photosensitive material such as dry film for photo-resister (DFR) or poly-imyde (PI).

The photosensitive material rapidly evaporates at a temperature of about 350 ° C., which is a thermogravimetric analyzer (TGA) at an insulator firing temperature, while maintaining the temperature of a sample at a constant rate or maintaining isothermal temperature in a specific gas atmosphere. By measuring the weight change of the sample with time and temperature, the increase or decrease of weight due to pyrolysis, sublimation, evaporation, and oxidation is analyzed using the pyrolysis curve). It can be seen that it exists.

The electron emission layer may be formed of a conical metal tip or a planar carbon-based material (graphite, carbon fiber, diamond-like carbon, carbon nanotube, etc.).

Hereinafter, exemplary embodiments of the present invention will be described in detail with reference to the accompanying drawings.

1 to 13 show schematic diagrams for explaining a manufacturing process of the field emission display device according to the present invention.

In order to manufacture the field emission display device, as shown in FIG. 1, a plurality of line-shaped cathode electrodes 12 are formed on the lower substrate 10. The cathode electrode 12 is generally formed of a metal such as chromium, silver, nickel, or indium tin oxide (ITO) in a thickness of 1000 to 3000 kPa. Here, as the method for forming the cathode electrode 12, a photolithography method, a thick film printing method, or the like may be selectively used according to the material of the electrode 12.                     

After the cathode electrode 12 is formed, as shown in FIGS. 2 to 4, a photosensitive film 14 is formed to cover the cathode electrode 12 (see FIG. 2), and the photosensitive film 14 is formed. The photosensitive pillars 18 are formed at portions where the negative holes (not shown) will be described later by exposing (see FIG. 3) and developing (not shown) using a known photo transfer process using the patterned mask 16. Form (see FIG. 4).

At this time, as a method of exposing the photosensitive film 14, either the front exposure method shown in FIG. 3 or a known back exposure method (not shown) can be used, and the height h of the photosensitive pillar 18 is 1 μm or more and 20. It is preferable to form lower than the insulating film (not shown) which will be described later in the range below micrometer, and the width w of the pillar 18 should be formed smaller than the hole width of the negative hole (not shown) which will be described later. desirable.

After the photosensitive pillar 18 is formed as described above, an insulating film 20 is formed to a thickness sufficient to cover the photosensitive pillar 18 as shown in FIG. 5.

In this case, the insulating film 20 may be formed by any one of a known printing method, an electrophoresis method, a doctor blade method, or a spray method. In this embodiment, an insulating film is formed by the printing method. Explain.

In order to form an insulating film by a printing method, an insulating paste must first be prepared. The insulating paste includes solvents such as terpineol, butyl carbitol (BC), butyl carbitol acetate (BCA), and the like. A vehicle is prepared by completely dissolving a binder such as ethyl cellulose (EC) and nitro cellulose (NC), and a solute obtained by uniformly mixing frit and insulating powder is vehicle. It can manufacture by mixing in.

After the insulation paste is manufactured, the paste is formed on the entire surface of the lower substrate 10. At this time, the insulating film 20 is about twice as high as the height h of the photosensitive pillar 18. It is preferable to form. This is because in order to minimize the undercut in consideration of the isotropy of the etching, it is most preferable to sink to the center of the insulator after firing.

Thereafter, the insulating film 20 is dried at 90 to 120 ° C. for 5 to 30 minutes.

After the drying operation is completed, the solvent and binder are removed by maintaining the temperature of 350 to 450 ° C. for 10 to 60 minutes, and then 5 to 60 minutes at a temperature of 20 to 30 ° C. higher than the softening point (450 to 550 ° C.) of the insulator frit. The firing of the insulating film 20 by maintaining the present invention is characterized in that the photosensitive pillar 18 is automatically removed during the firing operation of the insulating film 20.

To this end, the photosensitive film 14 forming the photosensitive pillar 18 may be made of a photosensitive material such as dry film for photo-resister (DFR) or poly-imyde (PI). This photosensitive material is rapidly evaporated at or below the firing temperature of the insulating film 20, for example, approximately 350 ° C.

Therefore, when the photosensitive pillar 18 is vaporized, the portion where the photosensitive pillar 18 is located inside the insulating film 20 remains in the empty space 22 as shown in FIG. 6, or as shown in FIG. 7. Likewise, a portion of the insulating film 20 that is above the photosensitive pillar 18 is recessed toward the empty space side.                     

The subsequent process will be described taking the case where a portion of the insulating film 20 is recessed.

As described above, when the photosensitive pillar 18 is removed and a portion of the insulating film 20 is recessed, the insulating film of the recessed portion (shown in dashed lines) is etched using the mask 24 as shown in FIG. 8. The negative hole 26 shown in FIG. 9 is completed.

In this case, hydrofluoric acid may be used as an etchant for etching the insulating film 20.

As such, the negative hole 26 can be completed by etching only a part of the insulating film 20 above the empty space 22 or a part of the insulating film 22 recessed into the empty space 22. The negative hole 26 has a cross-sectional shape that is close to the vertical (the same width as the upper and lower sides inside the hole) by minimizing the under-cut phenomenon due to the isotropy of etching.

Therefore, the negative hole 26 having a fine hole width can be formed.

Next, as shown in FIG. 10, a gate electrode 28 in a line is formed by a known thin film process or a thick film process, and a negative hole 26 and a gate hole 30 penetrating are formed by using an etching process. do. The gate electrode 28 is formed to vertically cross the cathode electrode 12 while surrounding the electron emission layer (not shown) forming portion, and the region where the cathode electrode 12 and the gate electrode 28 cross each other is an electron emission layer. This corresponds to the pixel region to be formed.

After the gate electrode 28 is formed as described above, as shown in FIGS. 11 and 12, an electron emission layer is formed on the cathode electrode 12 exposed to the inside of the negative hole 26. The electron emission layer may be formed of a known conical metal tip 32 (see FIG. 9), and may be graphite, carbon fiber, diamond like carbon (DLC), or carbon nanotubes. Carbon-based materials 32 'such as (CNT: Carbon Nano-Tube) may be printed and formed (see FIG. 10).

When the fabrication of the lower substrate is completed according to the above process, as shown in FIG. 13, the upper substrate 38 on which the anode electrode 34 and the fluorescent film 36 are formed by a separate process from the lower substrate 10. Is disposed in parallel with the lower substrate 10, and then the two substrates 10 and 38 are combined using the sealing material 40, thereby forming one sealed container for displaying the field emission. The hermetically sealed container is evacuated from its interior by an exhaust device (not shown) and finally completed as a field emission display device.

Although the preferred embodiments of the present invention have been described above, the present invention is not limited thereto, and various modifications and changes can be made within the scope of the claims and the detailed description of the invention and the accompanying drawings. Naturally, it belongs to the range of.

As described above, in the present invention, a negative hole is formed by using a photosensitive column formed by exposing and developing a photosensitive film, thereby fabricating a device having a negative hole having a very uniform size.

In addition, since only a part of the insulating film recessed above or inside the portion where the photosensitive pillar is located needs to be removed by etching, the undercut due to the isotropy of the etching can be minimized, which means that the vertical width (the upper and lower width inside the hole is the same). It is possible to form a negative hole having a cross-sectional structure and a fine hole width close to).

Therefore, it is possible to manufacture a high-definition device having fine pixels and to lower the gate driving voltage, which is advantageous in power consumption, driving circuit fabrication, and the like.

In addition, by forming the insulating film by using a thick film printing method, the process time for forming the insulating film can be shortened compared to the thin film process, and there is an effect such as low-cost manufacturing is possible.

Claims (6)

Forming a cathode on the lower substrate; Forming a photoresist film on the lower substrate; Exposing and developing the photosensitive film to form a photosensitive pillar at a position to form a negative hole; Forming an insulating film covering the photosensitive pillar; Firing the insulating film to vaporize the photosensitive pillar to dent a portion of the insulating film covering the pillar, or to form an empty space inside the insulating film; Etching the recessed portion or the portion with empty space to form a negative hole; Forming a gate electrode on the insulating layer, and etching the gate electrode to form a gate hole penetrating the negative hole; Forming an electron emission layer on the cathode electrode inside the negative hole; Arranging an upper substrate having an anode electrode and a fluorescent film substantially parallel to the lower substrate and combining the upper substrate to form a sealed container, and then evacuating the inside of the sealed container; Method of manufacturing a field emission display device comprising a. The method of claim 1, wherein the insulating layer is formed on the lower substrate by printing, electrophoresis, a doctor blade, or a spray method. The method of manufacturing a field emission display device according to claim 1, wherein the insulating film is fired by maintaining a temperature of 20 to 30 ° C. higher than the softening point of the insulator frit for 5 to 60 minutes. The method of claim 3, wherein the photoresist is made of dry film for photo-resister (DFR) or polyimide (PI). The method of claim 1, wherein the electron emission layer is formed of a conical metal tip. The method of claim 1, wherein the electron emission layer is formed of a planar carbon-based material.

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